What is colorectal cancer?
Colorectal cancer is a type of tumor that affects the colon and rectum, parts of the large intestine that play an important role in absorbing water, minerals, and forming stool.
These tumors usually begin as benign lesions in the large intestine (polyps). If detected early, these lesions can be removed before they turn into cancer. Therefore, colorectal cancer is a disease that can be prevented, treated, and often cured—especially when detected in its early stages.
Symptoms
Colorectal cancer often does not show symptoms in its early stages. However, as the disease progresses, signs may begin to appear. If you experience any of the symptoms below, it is important to consult a healthcare professional, as they may indicate cancer or other conditions that require attention:
- changes in bowel habits: such as diarrhea or (constipation)
- abdominal discomfort: such as frequent gas or cramps
- rectal bleeding or blood in the stool
- feeling that the bowel does not empty completely after a bowel movement
- unexplained weight loss
- excessive fatigue
- changes in stool: dark-colored stool or changes in consistency and shape (e.g., pasty or hard and pointed)
- nausea and vomiting
- pain in the anal area during bowel movements
- anemia of unknow origin
These symptoms can also occur in other diseases. Therefore, it is essential to consult a healthcare professional for an accurate diagnosis.
Causes
Several factors can increase the risk of developing colorectal cancer, such as:
- aging: age over 50
- family history of colorectal cancer
- medical history: having had ovarian, cervical or breast cancer, for example
- obesity and physical inactivity
- inflammatory bowel diseases: such as chronic ulcerative colitis or Crohn's disease
- hereditary conditions: such as familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), and other genetic syndromes related to hereditary cancer
Diagnosis
The diagnosis of colorectal cancer begins with an evaluation of the patient’s symptoms and medical history. Then, several tests may be requested, such as:
- fecal occult blood test: this test can help detect signs of bleeding in the intestines
- colonoscopy: a procedure in which a flexible tube with a camera is inserted through the rectum to examine the colon and rectum. During the procedure, the healthcare professional may identify and even remove small lesions or polyps
- biopsy: a test in which a small tissue sample is taken from a suspicious area, such as a lesion (polyp) or tumor, to be analyzed in a laboratory. This helps confirm whether the lesion is cancerous (and the type of tumor) or benign, by analyzing the characteristics of the cells
In addition to these tests, complementary imaging exams may be recommended, such as computed tomography (CT), magnetic resonance imaging (MRI), and in specific cases, positron emission tomography (PET-CT), to assess the extent of the cancer and determine whether the tumor has spread to other organs (metastasis). These exams help in planning the appropriate treatment and monitoring its progress.
Treatment
The treatment of colorectal cancer depends on the stage and location of the tumor. In general, the most common treatments include:
- surgery: to remove the tumor and, if necessary, affected parts of the intestine and nearby small structures that are part of the body's defense system (lymph nodes)
- radiotherapy: the use of radiation to destroy cancer cells or shrink the tumor
- chemotherapy: the use of drugs to destroy cancer cells and prevent the spread of cancer
For some types of intestinal cancer, additional treatments may be used, such as targeted therapies that directly attack cancer cells or immunotherapy, which helps the immune system fight the cancer. These are mainly used when the tumor has specific characteristics.
Einstein's Oncology and Hematology Department offers comprehensive care from diagnosis to treatment. Learn more.
Prevention
Although colorectal cancer can, in some cases, be related to hereditary factors (traits passed from parents to children) or chronic conditions such as type 2 diabetes mellitus, there are several actions that can help prevent it, including:
- maintaining a healthy diet: rich in fiber, with vegetables (such as broccoli and spinach), fruits (such as apples and oranges), whole grains (such as oats and brown rice), and legumes (such as carrots and beans)
- engaging in regular physical activity: 150 to 300 minutes per week
- avoiding unhealthy foods: such as alcoholic beverages, ultra-processed foods and meats, and excessive red meat
- maintaining a healthy weight: consult a healthcare professional for guidance on the appropriate weight for you
Screening
Early detection of colorectal cancer is important because, when diagnosed at an early stage, the disease has a higher chance of being cured. Since colorectal cancer may not show symptoms in its early stages, screening tests are recommended.
Screening should begin between the ages of 45 and 50 for the general population (this may vary depending on guidelines and risk factors). However, if there is a family history of colorectal cancer or personal or hereditary conditions that increase the risk, screening should start earlier.
The recommended screening tests generally include:
- fecal occult blood test
- flexible sigmoidoscopy
- colonoscopy (which allows visualization of the inside of the intestine)
It is essential to consult a healthcare professional to receive proper guidance on screening. The decision will take into account the patient’s specific case, personal and family history, to ensure the most appropriate test is chosen.
References
INSTITUTO NACIONAL DO CÂNCER (INCA). Radiotherapy, 2023
INSTITUTO NACIONAL DO CÂNCER (INCA). Chemotherapy, 2022
BRAZILIAN SOCIETY OF SURGICAL ONCOLOGY, how is colorectal cancer diagnosed?, 2022
National Comprehensive Cancer Network (NCCN). NCCN Guidelines Version 3.2024: Genetic/Familial High-Risk Assessment: Colorectal, Endometrial, and Gastric. Disponível em: https://www.nccn.org
National Comprehensive Cancer Network (NCCN). .NCCN Guidelines Version 1.2024: Colorectal Cancer Screening. Disponível em: https://www.nccn.org
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